feat: add 6.4 pipeline

[Michel (cyl3x)]

No description provided.

[Codecov Comments Bot (codecov-commenter)]

Codecov Report

Attention: Patch coverage is 0% with 24 lines in your changes missing coverage. Please review.

Please upload report for BASE (6.4.x@331306a). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
.php-cs-fixer.dist.php	0.00%	24 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             6.4.x     #83   +/-   ##
=======================================
  Coverage         ?   0.00%           
  Complexity       ?      68           
=======================================
  Files            ?      10           
  Lines            ?     250           
  Branches         ?       0           
=======================================
  Hits             ?       0           
  Misses           ?     250           
  Partials         ?       0           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Michel (cyl3x)]

I was unable to get any version of the extension store build to work in the administration, even when trying to build with Node.js 16. This could lead to non-working releases in the future, so it will not be merged.#

Edit: Relates to shopware/shopware-cli#575